C# – Suddenly application crash – Fatal Execution Engine Error (7A0BC59E) (80131506)

Completely random and suddenly our application crashes on its production environment. The application runs on Windows XP and .net framework 3.5 sp1. In the application we provide a WCF service and we use the serial port.

When the application crashes it leaves messages in the application log:

.NET Runtime version 2.0.50727.3625 - Fatal Execution Engine Error (7A0BC59E) (80131506)

 For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

and

Faulting application ***.exe, version 1.0.0.0, stamp 4f48b8fc, faulting module  mscorwks.dll, version 2.0.50727.3625, stamp 4e154c98, debug? 0, fault address 0x000a03ea.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

On our test environment we do have similar problems.

On the internet I find several identical problems, all mention hot fixes or reinstalls. But I want to know what happens and do not want happens. Does anyone knows what happens and how we can fix it?

[edit]
Besides the application also Sophos antivirus and MySql is installed.

[edit 2]
In our application we use a C-library wrapped in a .net package. We use the library in more applications and in those it does not give the exceptions.

[edit 3] Cannot answer my own question
Well I found something:

http://support.microsoft.com/kb/959209/en-us
958481 List of the issues that are addressed by the Application Compatibility Update for the .NET Framework 2.0 Service Pack 2

In the .NET Framework 3.5 SP1, because of the changes that are made in
checking a NULL value to support address space layout randomization
(ASLR), a failure case causes an access violation in the runtime. This
access violation manifests as an ExecutionEngineException exception.
Additionally, the process is terminated.

http://www.microsoft.com/download/en/details.aspx?amp;displaylang=en&id=10006